Micronized wood preservative formulations

ABSTRACT

The present invention provides wood preservative compositions comprising micronized particles. In one embodiment, the composition comprises dispersions of micronized metal or metal compounds. In another embodiment, the wood preservative composition comprises an inorganic biocide comprising a metal or metal compound and organic biocide. When the composition comprises an inorganic biocide and an organic biocide, the inorganic biocide or the organic biocide or both are present as micronized particles. When compositions of the present invention are used for preservation of wood, there is minimal leaching of the metal and biocide from the wood.

This application is a continuation-in-part of U.S. patent application Ser. No. 10/821,326, filed on Apr. 9, 2004, which claims the benefit of priority to U.S. Provisional Application Ser. No. 60/461,547, filed Apr. 9, 2003, and U.S. Provisional Application Ser. No. 60/518,994, filed Nov. 11, 2003, the disclosures of which are each incorporated herein by reference. This application is also a continuation-in-part of U.S. patent application Ser. No. 10/970,446 filed on Oct. 21, 2004, which claims the benefit of priority to U.S. Provisional Application Ser. No. 60/565,585, filed Apr. 27, 2004, the disclosures of which are each incorporated herein by reference.

FIELD OF THE INVENTION

The present invention is related generally to the field of wood preservatives and more particularly to a wood preservative composition comprising micronized metal biocides and fungicides.

BACKGROUND OF THE INVENTION

Wood-preserving compositions are well known for preserving wood and other cellulose-based materials, such as paper, particleboard, textiles, rope, etc., against organisms responsible for the destruction of wood, including fungi and insects. Many conventional wood-preserving compositions contain copper-amine complexes. Copper-amine complexes have been used to solubilize copper in aqueous solutions. The copper in such copper-amine complexes is obtained from a variety of copper bearing materials, such as copper scrap, cuprous oxide, copper carbonate, copper hydroxide, a variety of cuprous and cupric salts, and copper bearing ores. The amine in such copper-amine complexes is normally obtained from an aqueous solution of ammonia and ammonium salts, such as ammonium carbonate, and ammonium sulfate, ethanolamines, and the like. For example, U.S. Pat. No. 4,622,248 describes forming copper-amine complexes by dissolving copper (11) oxide [CuO] (also known as cupric oxide) in ammonia in the presence of ammonium bicarbonate.

The disadvantage of using ammonia as a copper solubilizing agent lies in the strong odor of ammonia. Additionally, copper-ammonia preservatives can affect the appearance of the treated wood giving surface residues and undesirable color. In recent years, many amine-containing compounds, such as alkanolamines and aliphatic polyamines, have been used to replace ammonia to formulate water-soluble copper solutions. These compounds were chosen because of their strong complexing ability with copper and because they are essentially odorless. U.S. Pat. No. 4,622,248 discloses a method of preparing copper-amine complexes by dissolving a mixture of copper (II) carbonate [CuCO₃] and copper (II) hydroxide [Cu(OH)₂] in ethanolamine and water. The complexing amine (i.e., the ligand) and copper (11) ion combine stoichiometrically and thus the weight ratio of reagents will be different for each complexing amine. However, copper-amine based preservatives have higher copper loss due to leaching as compared to traditional copper-based preservatives such as chromated copper arsenate (CCA).

In addition to metal biocides, existing wood preservatives can also contain organic biocides. However, many organic biocides currently in use are not water soluble. Therefore, solubilizing agents, surfactants and wetting agents are often added to either solubilize or form emulsions of the organic biocide to formulate a product that is suitable for the treatment of wood or other cellulose substrates.

However, the solubilizing agents, surfactants, and wetting agents are costly and the use of these products may result in enhanced leaching of the biocides when the treated material comes into contact with moisture. Such enhanced leaching is considered to be the result of the solubilizing agents, surfactants and wetting agents which remain in the wood after treatment. Because these compounds continue to cause leaching of the metal and/or biocide from the treated wood, field performance problems or environmental issues can result.

Despite many efforts to address these deficiencies in existing wood preservatives, there has been an unmet need to produce aqueous metal-based preservatives that are suitable for treating wood and other cellulose-based materials while minimizing the undesirable leaching of metal ions and/or biocide from treated materials when exposed to water. This need is met by the invention disclosed herein.

SUMMARY OF THE INVENTION

The present invention provides micronized compositions for preservation of wood. In one embodiment, the compositions comprise metal or metal compounds as micronized particles.

In another, embodiment, the compositions comprise metal or metal compounds and organic biocides. The metal is in an insoluble (micronized form). The metal compounds may be in a soluble form or in a water-insoluble (micronized) form. The organic biocides may be soluble or water insoluble (micronized or emulsified). In the compositions of this embodiment, at least one component (either a metal/metal compound or a biocide) is micronized. Accordingly, in one embodiment, the wood-preservative compositions of the present invention comprise a micronized metal, metal compounds or combinations thereof. In another embodiment, the wood-preservative compositions of the present invention comprise a micronized metal or metal compound and a soluble organic biocide. In another embodiment, the wood-preservative compositions of the present invention comprise a micronized metal or metal compound and a organic biocide emulsion. In another embodiment, the wood-preservative compositions of the present invention comprise micronized metal/metal compounds and micronized organic biocides. In yet another embodiment, the wood-preservative compositions of the present invention comprise a soluble metal compound and micronized organic biocides.

Also provided is a method for using the compositions of the present invention. The method comprises the step of contacting a cellulosic material, such as wood, with a composition of the present invention. When the compositions of the present invention are used for preservation of wood, there is minimal leaching of the metal or metal and the biocide from wood.

The present invention also provides cellulosic materials, including wood, paper, particleboard, textiles, rope, and the like, treated with the compositions of the present invention.

In one embodiment, the preferred metal for wood preserving type applications is copper in the form of a copper compound having a particle size 0.001 microns to 25.0 microns. The copper compound can optionally be mixed with a variety of water soluble and/or water insoluble biocides and then vacuum impregnated, vacuum/pressure or dip impregnated into cellulosic material by standard methods to effectively preserve the material from agents that degrade cellulosic material such as fungi, insects, bacteria etc.

The present invention provides an aqueous wood preservative composition comprising: (a) a micronized inorganic biocide and (b) one or more dispersants. In a preferred embodiment, the micronized inorganic biocide is at least one metal, at least one metal compound or combinations thereof. Preferably, the at least one metal is selected from the group consisting of copper, cobalt, cadmium, nickel, tin, silver, and zinc. More preferably, the at least one metal is copper.

In a preferred embodiment, the at least one metal compound is selected from the group consisting of a compound of copper, cobalt, cadmium, nickel, tin, silver, and zinc. More preferably, the at least one metal compound or complex is a copper compound or complex. Preferably, the copper compound or copper complex is copper hydroxide, copper oxide, copper carbonate, basic copper carbonate, copper oxychloride, copper 8-hydroxyquinolate, copper dimethyldithiocarbamate, copper omadine or copper borate. Most preferably, the copper compound is copper carbonate.

The wood preservative compositions of the present invention preferably comprise a micronized inorganic biocide with a particle size of between 0.001 microns and 25 microns. In another embodiment, the micronized inorganic biocide with a particle size of between 0.001 microns and 10 microns; between 0.05 to 10.0 microns; and between 0.05 to 1.0 microns.

The wood preservative compositions of the present invention preferably comprise a micronized inorganic biocide wherein the micronized inorganic biocide particles have a diameter less than 10 microns. In another embodiment, at least 98, 95, 90, 85, 80, 75, 70, 65, 60, 55, or 50% of the inorganic biocide particles (by weight) have a diameter less than 10 microns. In the compositions of the present invention, at least 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50% of the inorganic biocide particles (by weight) have a diameter of 0.5 microns or greater. In another embodiment, preferably 3 to 25% by weight, more preferably 3 to 10% by weight and still more preferably 3 to 5% by weight of the particles have a diameter of 0.5 microns or greater.

The present invention also provides micronized inorganic biocide compositions in concentrated form comprising between about 1 to 80% of the inorganic biocide by weight of the concentrated composition. In another embodiment, the inorganic biocide comprises 5 to 70% by weight of the concentrated composition. In yet another embodiment, the inorganic biocide comprises 30 to 65% by weight. In yet another embodiment, the compositions of the present invention comprise about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or 80% of the inorganic biocide by weight.

The present invention also provides micronized inorganic biocide compositions in concentrated form comprising an inorganic biocide and a dispersant, wherein the dispersant comprises between about 0.1 to 300% by weight of the inorganic biocide. In another embodiment, the dispersant comprises 5 to 150% by weight of the inorganic biocide. In another embodiment, the dispersant comprises 5 to 60%; 10 to 30%; 1 to 80%; 5 to 70%; or 30 to 65% by weight of the inorganic biocide.

In one embodiment, the dispersants used in the wood-preservative compositions of the present invention include, but are not limited to cationic, non-ionic or anionic dispersants, acrylic copolymers, an aqueous solution of copolymers with pigment affinity groups, polycarboxylate ethers, modified polyacrylates, acrylic polymer emulsions, modified acrylic polymers, poly carboxylic acid polymers and their salts, modified poly carboxylic acid polymers and their salts, fatty acid modified polyesters, aliphatic polyethers or modified aliphatic polyethers, polyetherphosphates, solution of polycarboxylate ethers, sodium polyacrylates, sodium polymethacrylates, modified polyether or polyester with pigment affinity groups, fatty acid derivatives, urethane copolymers or modified urethane copolymers, acrylic acid/maleic acid copolymers, polyvinyl pyyrolidones or modified polyvinyl pyrolidones, modified maleic anhydride/styrene copolymers, lignins and the like.

Preferably, the dispersants used in the wood-preservative compositions of the present invention are polymeric dispersants. In one embodiment, the polymeric dispersants contain at least one pigment affinity group capable of binding to a solid particle. In another embodiment, the polymeric dispersants stabilize a solid particle. Preferably, the polymeric dispersants used in the wood-preservative compositions of the present invention are modified polycarboxylate ethers, modified poly carboxylic acid polymers and their salts, solutions of polycarboxylate ethers and modified polyethers or polyesters with pigment affinity groups.

The present invention provides wood-preservative compositions comprising dispersants that function as a wetting agent/dispersing agent. In another embodiment, the dispersants of the present invention disperse the micronized particles of the wood-preservative compositions by reducing the size of particle aggregates. In one embodiment, the dispersants of the present invention disperse the micronized particles of the wood-preservative compositions by binding to the particle surface. In yet another embodiment, the dispersants of the present invention stabilize the micronized particles of the wood-preservative compositions during storage. In yet another embodiment, the dispersants of the present invention prevent flocculation. In one embodiment, the polymeric dispersants are capable of binding a solid particle at least one site on a solid particle surface. The affinity groups of the dispersants of the wood-preservative compositions of the present invention preferably bind a solid particle with high affinity and the polymeric chains of said dispersants preferably extend throughout a solvent system.

The dispersants of the present invention stabilize the micronized particles of the wood-preservative compositions during storage and during repetitive treatments. During repetitive treatment processes, pH change, wood extractives, wood sugars and contaminants from wood surfaces and dirt from air can each affect the function of dispersants and hence dispersed-particle stability.

The present invention also provides wood preservative compositions comprising an inorganic biocide, a dispersant, and further comprising a defoaming agent. Preferably, the defoaming agent is a silicon-containing defoaming agent or a silicon-free defoaming agent. In another embodiment, the defoaming agent is present in an amount between about 0.01 and 10% defoaming agent by weight.

The present invention also provides wood preservative compositions comprising an inorganic biocide, an organic biocide and one or more dispersants. Preferably, the organic biocide is an azole fungicide. In one embodiment, the azole fungicides comprise at least one imidazole or at least one triazole, or both. The present invention also provides wood preservative compositions comprising an inorganic biocide, an organic biocide and one or more dispersants. Preferably, the organic biocide is an azole fungicide. Typical examples of azole compounds include: 1-[[2-(2,4-dichlorophenyl)-1,3-dioxolan-2-yl]methyl]-1H-1,2,4-triazole(azaconazole), 1-[(2RS,4RS:2RS,4SR)-4-bromo-2-(2,4-dichlorophenyl)tetrahydrofurfuryl]-1H-1,2,4-triazole (bromuconazole), (2RS,3RS;2RS,3SR)-2-(4-chlorophenyl)-3-cyclopropyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol (Cyproconazole), (2RS,3RS)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-ol (diclobutrazol), cis-trans-3-chloro-4-[4-methyl-2-(1H-1,2,4-triazol-1-ylmethyl)-1,3-dioxolan-2-yl]phenyl 4-chlorophenyl ether (difenoconazole), (E)-(RS)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pent-1-en-3-ol (diniconazole), (E)-(R)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pent-1-en-3-ol (diniconazole-M), (2RS,3 SR)-1-[3-(2-chlorophenyl)-2,3-epoxy-2-(4-fluorophenyl)propyl]-1H-1,2,4-triazole (epoxiconazole), (RS)-1-[2-(2,4-dichlorophenyl)-4-ethyl-1,3-dioxolan-2-ylmethyl]-1H-1,2,4-triazole (etaconazole), (RS)-4-(4-chlorophenyl)-2-phenyl-2-(1H-1,2,4-triazol-1-ylmethyl)butyronitrile (fenbuconazole), 3-(2,4-dichlorophenyl)-6-fluoro-2-(1H-1,2,4-triazol-1-yl)quinazolin-4(3H)-one (fluquinconazole), bis(4-fluorophenyl)(methyl)(1H-1,2,4-triazol-1-ylmethyl)silane (flusilazole), (RS)-2,4′-difluoro-α-(1H-1,2,4-triazol-1-ylmethyl)benzhydryl alcohol (flutriafol), (2RS,5RS;2RS,5SR)-5-(2,4-dichlorophenyl)tetrahydro-5-(1H-1,2,4-triazol-1-ylmethyl)-2-furyl 2,2,2-trifluoroethyl ether (furconazole), (2RS,5RS)-5-(2,4-dichlorophenyl)tetrahydro-5-(1H-1,2,4-triazol-1-ylmethyl)-2-furyl 2,2,2-trifluoroethyl ether(furconazole-cis), (RS)-2-(2,4-dichlorophenyl)-1-(1H-1,2,4-triazol-1-yl)hexan-2-ol (hexaconazole), 4-chlorobenzyl (EZ)-N-(2,4-dichlorophenyl)-2-(1H-1,2,4-triazol-1-yl)thioacetamidate (imibenconazole), (1RS,2SR,5RS;1RS,2SR,5SR)-2-(4-chlorobenzyl)-5-isopropyl-1-(1H-1,2,4-triazol-1-ylmethyl)cyclopentanol (ipconazole), (1RS,5RS;1RS,5SR)-5-(4-chlorobenzyl)-2,2-dimethyl-1-(1H-1,2,4-triazol-1-ylmethyl)cyclopentanol (metconazole), (RS)-2-(4-chlorophenyl)-2-(1H-1,2,4-triazol-1-ylmethyl)hexanenitrile (myclobutanil), (RS)-1-(2,4-dichloro-β-propylphenethyl)-1H-1,2,4-triazole(penconazole), cis-trans-1-[2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-ylmethyl]-1H-1,2,4-triazole (propiconazole), (RS)-2-[2-(1-chlorocyclopropyl)-3-(2-chlorophenyl)-2-hydroxypropyl]-2,4-dihydro-1,2,4-triazole-3-thione (prothloconazole), 3-(2,4-dichlorophenyl)-2-(1H-1,2,4-triazol-1-yl)-quinazolin-4(3H)-one (quinconazole), (RS)-2-(4-fluorophenyl)-1-(1H-1,2,4-triazol-1-yl)-3-(trimethylsilyl)propan-2-ol (simeconazole), (RS)-1-p-chlorophenyl-4,4-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)pentan-3-ol (tebuconazole), propiconazole, (RS)-2-(2,4-dichlorophenyl)-3-(1H-1,2,4-triazol-1-yl)propyl 1,1,2,2-tetrafluoroethyl ether (tetraconazole), (RS)-1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-one (triadimefon), (1RS,2RS;1RS,2SR)-1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol (triadimenol), (RS)-(E)-5-(4-chlorobenzylidene)-2,2-dimethyl-1-(1H-1,2,4-triazol-1-ylmethyl)cyclopentanol (triticonazole), (E)-(RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pent-1-en-3-ol (uniconazole), (E)-(S)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pent-1-en-3-ol (uniconazole-P), and 2-(2,4-difluorophenyl)-1-(1H-1,2,4-triazole-1-yl)-3-trimethylsilyl-2-propanol. Other azole compounds include: amisulbrom, bitertanol, fluotrimazole, triazbutil, climbazole, clotrimazole, imazalil, oxpoconazole, prochloraz, triflumizole, azaconazole, simeconazole, and hexaconazole. Preferably, the azole fungicide is tebuconazole, propiconazole, simeconazole, cyproconazole or 2-(2,4-difluorophenyl)-1-(1H-1,2,4-triazole-1-yl)-3-trimethylsilyl-2-propanol. More preferably, the azole fungicide is tebuconazole. In one embodiment, the azole fungicide is solubilized, the azole fungicide is emulsified, or the azole fungicide is micronized. In another embodiment, the tebuconazole is solubilized; the tebuconazole is emulsified or the tebuconazole is micronized.

Preferably, the azole fungicide is a triazole compound such as tebuconazole, propiconazole, cyproconazole or 2-(2,4-difluorophenyl)-1-(1H-1,2,4-triazole-1-yl)-3-trimethylsilyl-2-propanol. More preferably, the azole fungicide is tebuconazole. In one embodiment, the azole fungicide is solubilized, the azole fungicide is emulsified, or the azole fungicide is micronized. In another embodiment, the tebuconazole is solubilized; the tebuconazole is emulsified or the tebuconazole is micronized.

The present invention also provides wood preservative compositions comprising an inorganic biocide, an organic biocide and one or more dispersants, wherein the weight ratio of the inorganic biocide to the organic biocide is from about 1000:1 to about 1:100. In another embodiment, the weight ratio of the inorganic biocide to the organic biocide is from about 500:1 to about 1:50. In another embodiment, the weight ratio of the inorganic biocide to the organic biocide is from about 100:1 to about 1:10. In a preferred embodiment, the weight ratio of the inorganic biocide to the organic biocide is from about 50:1 to about 1:1. In a more preferred embodiment, the weight ratio of the inorganic biocide to the organic biocide is from about 25:1 to about 5:1. In another embodiment, the weight ratio of the inorganic biocide to the organic biocide is about 10 to 1 or about 5 to 1.

The present invention also provides wood preservative compositions comprising a micronized copper carbonate, tebuconazole and one or more dispersants, wherein the weight ratio of the copper carbonate to the tebuconazole is about 100 to 1, about 50 to 1 and preferably about 25 to 1. In another embodiment, the weight ratio of the copper carbonate to tebuconazole is about 10 to 1 or about 5 to 1.

The present invention also provides methods for preserving a wood product comprising the step of contacting the wood product with the wood preservative compositions of the present invention. In one embodiment, the treatment of wood is carried out by a process selected from the group consisting of pressure treatment, spraying, dipping and brushing. Preferably, the treatment of wood is carried out by pressure treatment.

The present invention also provides a method of preparing a wood preservative composition comprising the step of mixing a micronized inorganic biocide and an organic biocide. In one embodiment, the micronized inorganic biocide is dispersed in water. In another embodiment, the water further comprises a dispersant. In another embodiment, the organic biocide is dissolved in an organic solvent or emulsified in water.

The present invention also provides a method of preparing a wood preservative composition comprising the step of mixing a micronized inorganic biocide and dispersant. In one embodiment, the methods of the present invention comprise the additional step of mixing an organic biocide with the micronized inorganic biocide and dispersant. In another embodiment, the method of preparing a wood preservative composition comprises the step of milling the composition. In a preferred embodiment, the milling produces a micronized inorganic biocide with a particle size of between about 0.001 microns and 25 microns; between about 0.001 to 10.0 microns between about 0.05 to 10.0 microns; or between 0.05 to 1.0 microns. In another embodiment, at least 98, 95, 90, 85, 80, 75, 70, 65, 60, 55, or 50% of the inorganic biocide particles (by weight) have a diameter less than 10 microns. In the compositions of the present invention, at least 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50% of the inorganic biocide particles (by weight) have a diameter of 0.5 microns or greater. In another embodiment, preferably 3 to 25% by weight, more preferably 3 to 10% by weight and still more preferably 3 to 5% by weight of the particles have a diameter of 0.5 microns or greater.

The present invention also provides wood comprising the wood preservative composition of the present invention, wherein a scanning electron microscopy image of a section of the wood identifies the existence of said micronized particles.

In another embodiment, the wood comprising the wood preservative composition of the present invention is resistant to decay and insect attack as determined by American Wood Preservers' Association Standard (AWPA) Standard E7-01 or AWPA Standard E10-01.

In yet another embodiment, the leaching of copper from the wood of the present invention is less than 50, 20, 10, 5, or, most preferably, 2% of the leaching of copper from wood containing more than 0.001 pcf of non-micronized copper, wherein leaching is measured according to modified American Wood Preservers' Association Standard E11-97.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts a comparison of copper leaching from wood treated with copper monoethanolamine (copper mea) vs. micronized copper hydroxide at copper retentions of 0.1 pounds per cubic foot (pcf) and 0.2 pcf according to American Wood Preservers' Association (AWPA) Standard E11-97 “Standard Method of Determining the Leachability of Wood Preservatives”.

FIG. 1B depicts a comparison of copper leaching from wood treated with a commercial copper based formulation ACQ-Type D and micronized copper carbonate plus dimethyldidecylammonium carbonate/bicarbonate (quat) at preservative retentions of 0.25 pcf and 0.40 pcf. The leaching test was conducted following the procedure described in AWPA Standard E11-97 “Standard Method of Determining the Leachability of Wood Preservatives”.

FIG. 2 depicts the anatomy of coniferous wood.

FIG. 3 depicts the border pit structure for coniferous wood.

FIG. 4A depicts the uniform copper penetration in wood treated with micronized copper hydroxide according to AWPA Standard A3-00 “Standard Method for Determining Penetration of Preservatives and Fire Retardants”.

FIG. 4B depicts the uniform copper penetration in wood treated with micronized copper carbonate plus quat. The determination of copper penetration was conducted following the procedures described in AWPA Standard A3-00 “Standard Method for Determining Penetration of Preservatives and Fire Retardants”.

FIG. 5 depicts the uniform particle distribution of cupric oxide through the cells of the wood treated with micronized CuO.

DETAILED DESCRIPTION OF THE INVENTION

Unless stated otherwise, such as in the examples, all amounts and numbers used in this specification are intended to be interpreted as modified by the term “about”. Likewise, all elements or compounds identified in this specification, unless stated otherwise, are intended to be non-limiting and representative of other elements or compounds generally considered by those skilled in the art as being within the same family of elements or compounds. The term “micronized” as used herein means a particle size in the range of 0.001 to 25 microns. Furthermore, it should be understood that “micronized” does not refer only to particles which have been produced by the finely dividing, such as by mechanical grinding, of materials which are in bulk or other form. Micronized particles can also be formed by other mechanical, chemical or physical methods, such as, for example, formation in solution, with or without a seeding agent, grinding or impinging jet. The term “preservative” as used herein means a composition that renders the material to which it is applied more resistant to insect, fungal and microbial attack than the same material without having the composition applied. The term “particle size” refers to the largest axis of the particle, and in the case of a generally spherical particle, the largest axis is the diameter.

The wood-preservative compositions of the present invention comprise an inorganic biocide comprising a metal, metal compound or combinations thereof and optionally one or more organic biocides. Accordingly, the present invention provides micronized wood preservatives comprising one or more metal or metal compounds with or without one or more organic biocides. When the composition comprises both the metal/metal compounds and the organic biocides, the metal or metal compounds or the organic biocides are present as water insoluble micronized particles. In one embodiment, both the inorganic biocide and the organic biocide are present as micronized particles.

These compositions are used for treatment of cellulosic material, such as wood. The leaching of metal from the treated wood is less for the present compositions than that observed from wood treated with non-micronized compositions.

A preferred metal is copper. Accordingly, in one embodiment, copper or copper compounds are used. The copper or copper compounds such as cuprous oxide (a source of copper (I) ions), cupric oxide (a source of copper (II) ions), copper hydroxide, copper carbonate, basic copper carbonate, copper oxychloride, copper 8-hydroxyquinolate, copper dimethyldithiocarbamate, copper omadine, copper borate, copper residues (copper metal byproducts) or any suitable copper source can be used as micronized particles having a particle size between 0.001 microns to 25 microns. These particles exhibit a relatively low solubility in water.

The copper source can be mixed with water with or without addition of a commercially available rheological additive such as a cellulosic derivative to form a finely dispersed suspension which can be mixed with a biocide to form a preservative system which is suitable to treat and protect wood from agents causing degradation. Other metals or metal compounds as well as transition metals or transition metal compounds (including the lanthanide and actinide series elements) such as tin, zinc, cadmium, silver, nickel, etc. and compounds thereof can be used in place of copper and copper compounds. The resulting metal dispersion or the metal biocide fluid dispersion are suitable for the preservation of wood and other cellulose-based materials.

The organic biocides useful in the present invention can be water soluble as well as water insoluble. Such organic biocides including fungicides, insecticides, moldicides, bactericides, algaecides etc. are well known to those skilled in the art and include azoles, quaternary ammonium compounds, borate compounds, fluoride compounds and combinations thereof. Some non-limiting examples of water-soluble biocides are quaternary ammonium compounds, such as alkyldimethylbenzylammonium chloride, dimethyldidecylammonium chloride, dimethyldidecylammonium carbonate/bicarbonate and the like. Water insoluble organic biocides are also well known.

Other biocides such as insecticides, mold inhibitors, algaecides, bactericides and the like, may also be added to the compositions of the present invention.

The insoluble biocides can be micronized into particles of submicron size ranging from 0.001 micrometers to 25 micrometers using a grinding mill. The particles are dispersed in standard dispersants such as acrylic copolymers, aqueous solution of copolymers with pigment affinity groups, modified polyacrylate, acrylic polymer emulsions, modified lignin and the like.

The compositions of the present invention can be adjusted to the desired pH. For example, the pH can be adjusted to between 2 to 13 by the addition of acids or alkaline components. The acid or alkaline components can be added before, during or after preparation of the micronized particles.

In the compositions of the present invention, at least 98, 95, 90, 85, 80, 75, 70, 65, 60, 55, or 50% of the particles (by weight) have a diameter less than 10 microns. In the compositions of the present invention, at least 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50% by weight have a diameter of 0.5 microns or greater. In another embodiment, preferably 3 to 25% by weight, more preferably 3 to 10% by weight and still more preferably 3 to 5% by weight of the particles have a diameter of 0.5 microns or greater.

In one embodiment, micronized metal or metal compounds such as a copper compound is mixed with an insoluble micronized organic biocide. The metal or metal compound and the insoluble biocide may be micronized separately and then mixed or may be mixed first and then micronized.

In another embodiment, the metal compound is water soluble. Examples of preferred water-soluble metal compounds are copper sulfate, copper acetate and copper nitrate. In this embodiment, an aqueous solution of the copper compound is prepared and then a micronized dispersion of an organic biocide is added to it.

Non-biocidal products such as water repellants (such as wax emulsions), colorants, emulsifying agents, dispersants, stabilizers, UV inhibitors, enhancing agents (such as trialkylamine oxides and alkoxylated diamines) and the like may also be added to the composition disclosed herein to further enhance the performance of the system or the appearance and performance of the resulting treated products. Those skilled in the art will recognize that some of these agents may also have some biocidal properties.

The wood preservative compositions of the present invention may be formulated by several methods. In one embodiment, the wood preservative compositions may be prepared by diluting or mixing a concentrate of a micronized inorganic biocide and an organic biocide with water or another component. In another embodiment, a micronized inorganic biocide is mixed with an organic biocide.

The organic biocides of the wood preservative compositions of the present invention may be provided as a solution in one or more organic solvents, an emulsion in water by emulsifying the compounds with the aid of one or more emulsifiers, or as a dispersion of micronized particles of organic biocide in water.

Non-limiting examples of solvents used for dissolving the organic biocides of the present invention, include dichloromethane, hexane, toluene, alcohols such as methanol, ethanol, and 2-propanol, glycols such as ethylene glycol and propylene glycol, ethers, esters, poly-glycols, poly-ethers, amides, methylene chloride, acetone, chloroform, N,N-dimethyl octanamide, N,N-dimethyl decanamide, N-methyl 2-pyrrolidone, n-(n-octyl)-2-pyrrolidone, and combinations of the above.

In on embodiment, the micronized particles are dispersed by homogenization or high speed agitation or by milling or grinding the organic biocide or by any other chemical or physical means. The micronized particles may be dispersed using dispersants known in the art. Suitable dispersants for use in the wood preservative compositions of the present invention, include cationic, non-ionic or anionic dispersants, acrylic copolymers, an aqueous solution of copolymers with pigment affinity groups, polycarboxylate ethers, modified polyacrylates, acrylic polymer emulsions, modified acrylic polymers, poly carboxylic acid polymers and their salts, modified poly carboxylic acid polymers and their salts, fatty acid modified polyesters, aliphatic polyethers or modified aliphatic polyethers, polyetherphosphates, modified maleic anhydride/styrene copolymers, lignins and the like.

The organic biocides of the wood preservative compositions of the present invention may be provided as an emulsion in water by emulsifying the compounds with the aid of one or more emulsifiers. Emulsifers may be anionic, cationic, or nonionic or combinations thereof. Examples of emulsifers include, but are not limited to, ethoxylated alkylphenols, amines, amides, aryl phenols, fatty esters, fatty acids and derivatives, ethoxylated alcohols and derivatives, sulfonated amines, carboxylated alcohols, alkylphenol ethoxylates, glycol ethers or glycol esters. Additional examples of emulsifers may be found in McCutcheon's Emulsifiers and Detergents, 2005, which is incorporated herein by reference, in its entirety.

For metal or metal compound biocides, the level of dispersant is in the range of from about 0.1 to 180% of the weight of the biocide compounds, with a preferred range of 1 to 80%, a more preferred range of 5 to 60%, and a most preferred range of 10 to 30%. For organic biocides, such as, for example, tebuconazole, cyproconazole, imidacloprid, chlorothalonil, etc, the level of dispersant is in the range of from about 1 to 200% of the weight of the biocide compounds, with a preferred range of 5 to 100%, a more preferred range of 10 to 80%, and a most preferred range of 30 to 70%.

In another embodiment, for metal or metal compound biocides, the level of dispersant is in the range of about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200% of the weight of the biocide compounds

In the present invention, the concentrates of inorganic biocide(s) and organic biocide(s) can be prepared separately and then mix together with water to make a preservative treating composition in wood preservative treating plants. Optionally, a blended concentrate containing inorganic biocide(s) and organic biocide(s) can be prepared and then dilute with water to make a preservative treating composition. The total active ingredients of the preservative treating compositions can vary from 0.001% to 50.0% depending upon the preservative systems, preferably 0.01% to 10.0%, and more preferably from about 0.1% to 3.0%. The compositions of the present invention can be a concentrate or a preparation which is ready to apply to wood. In general, when preparing a biocide concentrate, the total biocide content of the concentrate is in the range of from 1 wt % to 80 wt %, based on weight of composition, and preferably in the range of from 5 to 70 wt %, and more preferably in the range of from 30 to 65 wt %.

In a preferred embodiment, the micronized particles of the present invention are produced by grinding. For example, a slurry comprising a dispersant, a carrier, and a powdered biocide may be ground in the methods of the present invention to a particle size in the range of from 1 micron to 500 microns. In one embodiment, the methods of the present invention optionally contain a defoamer. In one method, the slurry is transferred to a grinding mill that is pre-filled with a grinding media having a size from 0.05 mm to 5 mm, and preferably between 0.1 and 1 mm. The media can be one or more of many commercially-available types, including but not limited to steel shot, carbon-steel shot, stannous-steel shot, chrome-steel shot, ceramic shot (for example, alumina-containing); zirconium-based shot, such as zirconia, zirconium silicate, zirconium oxide; stabilized zirconia such as stabilized ytz-stabilized zirconia, ceria-stabilized zirconia, stabilized magnesium oxide, stabilized aluminum oxide, etc. The grinding medium preferably occupies 50% to 99% of the grinding chamber volume, with 75 to 95% preferred, and 80 to 90% even more preferred. The bulk density of the grinding media is preferably in the range of from 0.5 kg/l to 10 kg/l, and more preferably in the range of from 2 to 5 kg/l. Agitation speed, which can vary with the size of the grinder, is generally in the range of from 1 to 5000 rpm, but can be higher or lower. A set up which involves a transfer pump which repeatedly cycles the slurry between the mill and a storage tank during grinding is preferred. The transfer pump speed may vary from 1 to 500 rpm. During grinding, defoamer may be added if foaming is observed. During grinding, particle size distribution may be analyzed, and once particle size is within the desired specification, grinding may be stopped.

When wood is treated with micronized wood preservatives formulations disclosed herein, metal leaching is reduced. For example, as shown in FIG. 1A, when wood is treated with Cu-MEA composition the leaching of copper is about 12% and 24% respectively for 0.1 pcf (pounds per cubic feet) copper and 0.2 pcf copper. In contrast when the wood is treated with a micronized composition of the present invention the leaching was only about 2% and 1% respectively for the 0.1 pcf copper and 0.2 pcf copper. Copper leaching was evaluated following the procedures described in American Wood Preservers' Association Standard E11-97.

Wood treated with the micronized preservatives of the present invention exhibits reduced leaching. Accordingly, if wood is treated with micronized copper, copper 30 compounds, copper complexes or combinations thereof such that copper or copper ions are present at a concentration of greater than 0.001 pcf, the leaching of copper from the wood is less that 50% of leaching observed with non-micronized formulations. In another embodiment, at concentrations of copper or copper ions in treated wood greater than 0.001 pcf, the leaching of copper is less than 20% of leaching observed with non-micronized formulations. In yet another embodiment, at concentrations of copper or copper ions in treated wood between 0.001 and 0.05 pcf, the leaching of copper is less than 20% of leaching observed from wood containing greater than 0.001 pcf of non-micronized copper. Preferably, the leaching of copper is less 10%, and more preferably less than 5%, of leaching observed with non-micronized copper formulations when the concentration of copper or copper ions is between 0.001 to 0.5 pcf.

The present invention is not limited to applications which involve micronized particles which have been applied to wood as such. For example, the wood preservative effect of micronized particles can be realized by the formation of such particles in situ. By in situ, it is meant that particle formation takes place on or within the wood. Thus, the benefits of the present invention can be realized if particle formation takes place, for example, within the tracheids of the wood to be preserved. Additionally or instead, particle formation can take place outside of the tracheids, with the subsequent movement of at least some of the particles into the tracheids. Such a movement can be caused by, for example, pressure cycling, such as described in the examples. The micronized particles generally have an average size which is small enough to enable at least partial penetration of wood by particle migration through tracheids and border pits.

It should be understood that unless specifically set forth in conjunction with a method, the term “treatment” as used herein should not be construed as pertaining only to the application of micronized particles to wood which is to be preserved, but also includes in situ formation of micronized formation. Thus, the term “treatment,” should generally be construed to encompass all methods as a result of which micronized particles are present in the wood. Thus, the term “treated wood” is only intended to mean wood comprising micronized particles, irrespective of the mode of formation/delivery of the micronized particles.

Similarly, FIG. 1B is a comparison of copper leaching from wood treated with a commercial copper based formulation ACQ-Type D and micronized copper carbonate plus dimethyldidecylammonium carbonate/bicarbonate (quat) at preservative retentions of 0.25 pcf and 0.40 pcf. The leaching test was conducted following the procedure described in AWPA Standard E11-97 “Standard Method of Determining the Leachability of Wood Preservatives”. It can be seen that wood treated with micronized copper carbonate based formulation demonstrated much greater copper leaching resistance than the wood treated with the commercially available preservative Ammoniacal Copper Quat (ACQ)-Type D.

Also important is the penetration of the dispersion formulation into the wood's or other cellulose-based material's cellular structure. If the copper source used in formulating the dispersion formulation disclosed herein has a particle size in excess of 25 microns, the particles may be filtered by the surface of the wood and thus may not be uniformly distributed within the cell and cell wall. As shown in FIG. 2, the primary entry and movement of fluids through wood tissue occurs primarily through the tracheids and border pits. Tracheids have a diameter of about thirty microns. Fluids are transferred between wood cells by means of border pits.

The overall diameter of the border pit chambers typically varies from a several microns up to thirty microns while, the diameter of the pit openings (via the microfibrils) typically varies from several hundredths of a micron to several microns. FIG. 3 depicts the border pit structure for coniferous woods.

When wood is treated with micronized preservative formulation, if the particle size of the micronized preservative is less than the diameter of the pit openings, a complete penetration and a uniform distribution of micronized preservative in wood is expected. FIG. 4A depicts the complete copper penetration in wood treated with micronized copper hydroxide according to AWPA Standard A3-00 “Standard Method for Determining Penetration of Preservatives and Fire Retardants”. A uniform blue was observed indicating the presence of copper. FIG. 4B depicts the complete copper penetration in wood treated with micronized copper carbonate plus quat. Again, a uniform blue color was observed indicating the presence of copper. The determination of copper penetration was conducted following the procedures described in AWPA Standard A3-00 “Standard Method for Determining Penetration of Preservatives and Fire Retardants”. FIG. 5 depicts the uniform particle distribution of cupric oxide through the cells of the wood treated with micronized CuO through the observation of Scanning Electron Microscope (SEM). The particles were confirmed to be copper compounds by the use of SEM-Energy Dispersed X-ray Analysis (EDXA).

Particle size of the metal, metal compounds or organic biocide used in the dispersion formulation disclosed herein typically does not exceed 30 microns or the metal and or organic biocide used in conjunction with the metal tends to be filtered by the surface of the wood thus not attaining a desired penetration and fluid flow through the wood tissue. In one embodiment particle size of the micronized particles used in the dispersion formulation disclosed herein can be between 0.001-10 microns. In another embodiment, the particle size is between 0.001 to 1.0 micron. In another embodiment, the particle size is between 0.05 to 10.0 microns. If a more uniform penetration is desired, particle size of the metal/metal compounds or the organic biocide used in the dispersion formulation disclosed herein can be between 0.05-1.0 microns.

The present invention also provides a method for preservation of wood. In one embodiment, the method comprises the steps of treating wood with a composition (treating fluid) comprising a dispersion of water insoluble micronized metal and/or metal compounds. In another embodiment, wood is treated with a composition comprising a dispersion of micronized metal and/or metal compounds and organic biocides, wherein the organic biocides are soluble or present as water insoluble micronized particles. The size of the micronized particles for the metal/metal compounds and organic biocide is between 0.001 to 25 microns, preferably between 0.001 to 10 microns, more preferably between 0.05 to 10 micron and even more preferably between 0.05 to 1.0 microns. In another embodiment, the wood is treated with a composition comprising soluble metal compounds and micronized organic biocides.

The treating fluid may be applied to wood by dipping, soaking, spraying, brushing, or any other means well known in the art. In a preferred embodiment, vacuum and/or pressure techniques are used to impregnate the wood in accord with this invention including the standard processes, such as the “Empty Cell” process, the “Modified Full Cell” process and the “Full Cell” process, and any other vacuum and/or pressure processes which are well known to those skilled in the art.

The standard processes are defined as described in AWPA Standard C1-03 “All Timber Products—Preservative Treatment by Pressure Processes”. In the “Empty Cell” process, prior to the introduction of preservative, materials are subjected to atmospheric air pressure (Lowry) or to higher air pressures (Rueping) of the necessary intensity and duration. In the “Modified Full Cell”, prior to introduction of preservative, materials are subjected to a vacuum of less than 77 kPa (22 inch Hg) (sea level equivalent). A final vacuum of not less than 77 kPa (22 inch Hg) (sea level equivalent) shall be used. In the “Full Cell Process”, prior to introduction of preservative or during any period of condition prior to treatment, materials are subjected to a vacuum of not less than 77 kPa (22 inch Hg). A final vacuum of not less than 77 kPa (22 inch Hg) is used.

EXAMPLES

The following examples are provided to further describe certain embodiments of the invention but are in no way meant to limit the scope of the invention. Examples 1 through 5 demonstrate the formulation of the concentrated dispersions of copper compounds and the concentrated dispersions of copper compounds comprising various organic biocides. Examples 6 through 14 demonstrate the preparation of treating fluids using concentrated dispersions for the treatment of wood.

Example 1

500 g of copper hydroxide were added to a container containing 1091.7 grams of water and 75.0 grams of commercially available dispersants/wetting agents. The mixture was mechanically stirred for 5 minutes and then placed in a grinding mill. The sample was ground for about 30 minutes, and a stable dispersion containing about 30% copper hydroxide was obtained. The particle size of the copper hydroxide dispersion was analyzed by Horiba LA-910 Particle Size Distribution Analyzer (PSDA). The average particle size was 0.195 micrometers (um) with a distribution range of 0.04 μM to 1.5 um.

Example 2

1000 grams of basic copper carbonate was mixed with 2158.3 grams of water and 175.0 grams of commercially available wetting agents/dispersants. The mixture was mechanically stirred for 10 minutes. The mixture was then placed in a grinding mill and ground for about 20 minutes. A stable dispersion was obtained with an average particle size of 0.199 micrometers.

Example 3

1000 grams of basic copper carbonate and 20 grams of tebuconazole were mixed with 3780 grams of water and 200 grams of wetting agents/dispersants. The mixture was mechanically stirred for about 10 minutes. The mixture was then placed in a grinding mill and ground for about 30 minutes. A stable dispersion containing 25% basic copper carbonate and 0.5% tebuconazole was obtained with an average particle size of 0.200 micrometers.

Example 4

300 grains of copper 8-hydroxyquinolate (Cu-8) were mixed with 855 grains of water and 45 grams of dispersants. The mixture was mechanically mixed for about 5 minutes and placed in a grinding mill. The mixture was ground for about 30 minutes and a stable dispersion containing 25% Cu-8 was obtained with an average particle size of 0.282 micrometers.

Example 5

A stable cupric oxide (CuO) dispersion containing about 30% CuO was supplied by Nanophase Technologies, Inc. The average particle size was about 0.1 micrometers. This can be mixed with organic soluble or micronized biocides.

Example 6

38.5 g of cupric hydroxide dispersion from Example 1 was mixed with 7.5 g of N,N-dimethyl-1-dodecylamine-N-oxide (AO) and 2954.0 g of water to produce a preservative treating fluid containing 0.385% cupric hydroxide and 0.25% AO. The fluid was then used to treat 2″×4″×10″ samples of southern pine sapwood, and sealed with epoxy resin, using an initial vacuum of 28″ Hg for 15 minutes, followed by a pressure cycle of 135 psi for 25 minutes and a final vacuum of 27″ Hg for 10 minutes. The resulting treated wood was weighed and found to have doubled its weight. The treated sample was cut and the cross sections sprayed with a copper indicator to determine copper penetration following the procedure described in American Wood Preservers' Association Standard A3-00, and the blue color indicates the presence of copper. The sample was found to have 100% uniform distribution of copper throughout the cross section as in FIG. 4A. As a comparison, FIG. 4A also showed the cross section of untreated wood.

Example 7

50.0 g CuO dispersion from Example 5 were mixed with 2942.5 g of water and 7.5 g of didecyldimethylammonium chloride. The product was mixed until uniformly dispersed and the treating solution containing the following compositions was obtained: 2 Components Percent Cupric Oxide 0.50 Didecyldimethylammonium Chloride 0.25

A southern pine stake measuring 1.5″×3.5″×10″ was placed in a laboratory retort with a vacuum of 27″ Hg for 15 minutes. The treating solution was then pumped into the retort and the retort pressurized to 130 psi for 30 minutes. The solution was drained from the retort and the test stake weighed. Based on the weight pickup, the test stake doubled its weight and showed uniform penetration of the cupric oxide throughout the wood cross section. A sample taken from the center portion of the treated wood was submitted for scanning electron microscopy (SEM) analysis, and the SEM result indicated the uniform particle distribution in wood as shown in FIG. 5.

Example 8

4000 g of treating fluid containing 0.31% of cupric oxide and 0.16% didecyldimethylammonium carbonate were prepared by mixing CuO dispersion from Example 5 and didecyldimethylammonium carbonate. The fluid was used to treat 2″×4″×10″ southern pine samples by placing the samples in a chamber and drawing a 27″ Hg vacuum for 10 minutes. The treating fluid was then drawn into the chamber and allowed to stay in contact with the wood cubes for 15 minutes. The fluid was pumped from the chamber and the resulting wood had more than doubled its weight. Cross sections of the cubes showed 100% copper penetration.

Example 9

A preservative treating formulation was prepared by adding 0.15 kg of copper carbonate dispersion from Example 2 to 0.025 kg of N,N-dimethyl-1-hexadecylamine-N-oxide and 4.825 kg of water. This fluid was allowed to mix until a homogenous fluid was prepared. This fluid was used to treat southern pine test stakes measuring 0.156×1.5×1-0.0 inches (4×38×254 mm) by the full-cell process. The resulting stakes showed a uniform distribution of copper throughout the wood cells. The treated test stakes were installed in the field to evaluate the field performance of the preservative following the procedure described in AWPA Standard E7-01 “Standard Method of Evaluating Wood Preservatives by Field Tests with Stakes”. The test results indicated that the treated stakes were resistant to decay and insect attack. The fluid was also used to treat southern pine wood cube blocks measuring ¾″×¾″×¾″ (19 mm×19 mm×19 mm). The treated cubes were exposed to several test fungi to evaluate the bio-efficacy of the preservative formulation following the procedure described in AWPA Standard E10-01 “Standard Method of Testing Wood Preservatives by Laboratory Soil-Block Cultures”. Upon the completion of the soil-block test, the cubes were found to have less than 2.0% weight loss, indicating essentially no fungal attack to the treated cubes. In comparison, untreated wood cubes had approximately 50% weight loss after being exposed to the test fungi. The soil block test results indicated wood treated the above preservative formulation was resistant to fungal attack.

Example 10

A preservative treating composition was prepared by adding 0.1 kg of dispersion from Example 3 to 4.9 kg of water. The resulting fluid contained 0.50% copper carbonate and 0.01% tebuconazole. This fluid was then used to treat full-size lumber using the full-cell process wherein the wood is initially placed under a vacuum of 30″ Hg for 30 minutes, followed by the addition of the treating solution. The system was then pressurized for 30 minutes at 10 psi. A final vacuum of 28″ Hg for 30 minutes was applied to the wood to remove residual liquid. The wood was found to contain a uniform distribution of copper throughout the cross sections and is resistant to fungal and insect attack.

Example 11

54 g of dispersion from Example 3 and 7.5 g of N,N-dimethyl-1-hexadecylamine-N-oxide (AO) were mixed with 2938.5 grams of water to obtain a preservative treating fluid containing 0.45% carbonate, 0.009% tebuconazole and 0.25% AO. The resulting fluid was used to treat red pine lumber using a modified full-cell process. The resulting stakes were air-dried and found to a uniform distribution of copper throughout the cross sections and were resistant to fungal and insect attack.

Example 12

A preservative treating fluid was prepared by adding 16.0 g of Cu 8-hydroxyquinolate (Cu-8) dispersion from Example 4 to 3984.0 g of water. The resulting fluid contained 0.1% Cu-8. The fluid was used to treat southern pine lumber using a full cell process. The treated stakes were oven dried and found to contain a uniform distribution of particles throughout the cross sections and were resistant to fungal and insect attack.

Example 13

A preservative treating fluid was prepared by mixing 175 g concentrated dispersion containing 20% copper carbonate and 0.5% cyproconazole with 3325.0 g water. The resulting solution contained 1.0% copper carbonate and 0.025% cyproconazole and was used to treat southern pine lumber using a full cell process. The treated stakes were oven dried and found to contain a uniform distribution of copper and cyproconazole throughout the cross sections and were resistant to fungal and insect attack.

Example 14

A preservative treating fluid can be prepared by mixing copper sulfate solution and micronized cyproconazole at a concentration of 0.25% Cu and 0.01% cyproconazole. The resulting fluid can be used to treat lumber using a full cell process. The treated sample can be air-dried for two weeks and tested for resistance to fungal and termite attack.

Although specific embodiments have been described herein, those skilled in the art will recognize that routine modifications can be made without departing from the spirit of the invention.

Example 15

Two wood-treatment compositions were compared in an accelerated laboratory test using the copper-tolerant fungi C. puteana and P. placenta. The testing was performed following the procedure described in American Wood Preservers' Association (AWPA) Standard E10-OL: “Standard Method of Testing Wood Preservatives by Laboratory Soil Block Cultures”. The results of this comparison are presented in Table 1.

TABLE 1 Accelerated Laboratory Soil Block Test of Micronized Copper Formulations against Copper Tolerant Fungi Retention Weight Loss, % Treatment (kg/m3) C. puteana P. placenta Untreated Control 0.0 47.6 53.4 Micronized Copper 0.8 Cu 49.2 37.8 Carbonate 1.6 Cu 46.6 33.2 2.4 Cu 51.6 27.3 3.2 Cu 46.1 39.5 Micronized Copper 0.8 Cu + 0.032 2.7 0.0 Carbonate + Tebuconazole Tebuconazole 1.6 Cu + 0.064 0.0 0.0 Tebuconazole 2.4 Cu + 0.096 0.0 0.0 Tebuconazole 3.2 Cu + 0.128 0.0 0.0 Tebuconazole

Example 16

Two wood-treatment compositions were compared in a 12-month field study. The field performance test was evaluated following the procedure described in American Wood Preservers' Association (AWPA) Standard E7-01: “Standard Method of Evaluating Wood Preservatives by Field Tests with Stakes”. The results of this comparison are presented in Table 2. The numerical decay rating system is described in Table 3.

TABLE 2 Average Decay Ratings of a Micronized Copper/Tebuconazole Preservative Treated Wood Stakes (4 × 38 × 254 mm) Installed in Gainesville, Florida for 12 months Retention Treatment (kg/m3) Decay Rating Untreated Control 0.0 3.8 Tebuconazole 0.32 Tebuconazole 8.2 0.48 Tebuconazole 5.8 0.64 Tebuconaozle 8.7 Micronized Copper 0.8 Cu + 0.032 Tebuconazole 10.0 Carbonate + 1.6 Cu + 0.064 Tebuconazole 10.0 Tebuconazole 2.4 Cu + 0.096 Tebuconazole 10.0 3.2 Cu + 0.128 Tebuconazole 10.0

TABLE 3 Description of numerical decay ratings. Decay Rating Description 10 Sound (suspicion of decay permitted) 9 Trace decay to 3% of cross section 8 Decay from 3 to 10% of cross section 7 Decay from 10 to 30% of cross section 6 Decay from 30 to 50% of cross section 4 Decay from 50 to 75% of cross section 0 Failure 

1. An aqueous wood preservative composition comprising: (a) a micronized inorganic biocide; (b) one or more dispersants; and optionally (c) an organic biocide.
 2. The composition of claim 1, wherein the micronized inorganic biocide is at least one metal, at least one metal compound or combinations thereof.
 3. The composition of claim 2, wherein the at least one metal is selected from the group consisting of copper, cobalt, cadmium, nickel, tin, silver, and zinc.
 4. The composition of claim 2, wherein the at least one metal compound is selected from the group consisting of a compound of copper, cobalt, cadmium, nickel, tin, silver, and zinc.
 5. The composition of claim 3, wherein the at least one metal is copper.
 6. The composition of claim 4, wherein the at least one metal compound is a copper compound.
 7. The composition of claim 6, wherein the copper compound is copper hydroxide, copper oxide, copper carbonate, basic copper carbonate, copper oxychloride, copper 8-hydroxyquinolate, copper dimethyldithiocarbamate, copper omadine or copper borate.
 8. The composition of claim 7, wherein the copper compound is copper carbonate. 9-12. (canceled)
 13. The composition of claim 1, wherein at least 98% of the micronized inorganic biocide particles have a diameter less than 10 microns and at least 3% of the micronized inorganic biocide particles have a diameter of 0.5 microns or greater. 14-15. (canceled)
 16. The composition of claim 1, wherein the dispersant comprises 0.1 to 150% by weight of the inorganic biocide. 17-24. (canceled)
 25. The composition of claim 1, wherein the dispersant is cationic, anionic or non-ionic.
 26. The composition of claim 1, wherein the dispersant is selected from the group consisting of acrylic copolymers, copolymers with pigment affinity groups, polycarboxylate ethers, modified polyacrylates, acrylic polymer emulsions, modified acrylic polymers, polycarboxylate polymers and their salts, modified polycarboxylate acid polymers and their salts, fatty-acid-modified polyesters, aliphatic polyethers, modified aliphatic polyethers, polyetherphosphates, modified maleic anhydride/styrene copolymers, and lignin.
 27. The composition of claim 1, wherein the organic biocide is an azole fungicide. 28-33. (canceled)
 34. The composition of claim 27, wherein the azole fungicide is solubilized.
 35. The composition of claim 27, wherein the azole fungicide is emulsified.
 36. The composition of claim 27, wherein the azole fungicide is micronized.
 37. The composition of claim 27, wherein the azole fungicide is tebuconazole, propiconazole, cyproconazole or 2-(2,4-difluorophenyl)-1-(1H-1,2,4-triazole-1-yl)-3-trimethylsilyl-2-propanol.
 38. The composition of claim 37, wherein the azole fungicide is tebuconazole. 39-42. (canceled)
 43. The composition of claim 1, wherein the weight ratio of the inorganic biocide to the organic biocide is about 500 to
 1. 44. The composition of claim 1, wherein the weight ratio of the inorganic biocide to the organic biocide is about 100 to
 1. 45-74. (canceled)
 75. Wood comprising the wood preservative composition of claim 1, wherein a scanning electron microscopy image of a section of the wood identifies the existence of said micronized particles.
 76. Wood comprising the wood preservative composition of claim 27, wherein a scanning electron microscopy image of a section of the wood identifies the existence of said micronized particles.
 77. The wood of claim 1, wherein the wood is resistant to decay and insect attack as determined by American Wood Preservers' Association Standard (AWPA) Standard E7-01 or AWPA Standard E10-01. (91) 78-84. (canceled) 